Apparatus for advancing strands



June 10, 1952 s. w. BARKER 2,599,603

APPARATUS FOR ADVANCING STRANDS Filed Feb. 21. 1947 INVENTOR SYDNEY WARREN BARK ER m ATTORNEY Patented June 10, 1952 APPARATUS FOR ADVANCING STRANDS Sydney Warren Barker, Colne, England, assignor to Lustrafil Limited, a corporation of Great Britain Application February 21, 1947, Serial No. 729,999 In Great Britain February 23, 1946 7 Claims.

This invention relates to apparatus for guidin rayon and generally similar artificial threads or filaments. More particularly it relates to apparatus for maintaining properly uniform threadloop spacing through prevention of thread wobble which tends to occur in the manufacture of such threads by a continuous process involving employment of a pair of positively driven mutually inclined rollers arranged substantially one above the other, along which the thread. issuing from the spinning bath advances under slight tension, insufficient to impart to it a permanent stretch, in a series of spaced helical loops and during its traverse is treated with liquid. The aforesaid tendency of the thread to wobble is corrected, in accordance with the principles of the invention, by increasing the tension of the thread in its upward path of travel, at those parts of the traverse where the thread is wet, to only a slight extent; this being accomplished mechanically by so peripherally contouring and driving said rollers relatively to each other that the effective peripheral speed of the upper roller, at those parts of the traverse where the thread is wet and under only slight tension, is slightly greater than that of the lower roller to the extent required to produce the slight increase in thread tension aforesaid.

In continuous processes of manufacturing artificial threads or filaments, it is broadly old to pass the thread in a series of helical loops around a pair of rollers rotating upon shafts which are inclined to one another, both being positively driven. The thread may during its traverse of the pair of rollers be subjected to various successive treatments such as completion of coagulation, washing, drying, bleaching and the like.

For many purposes it is desirable that the 2 rollers to become slacker than the downwardmoving part. This is seen shortly after startingup or re-starting as a more or less marked wobble of the upward-moving thread, and the loops fail to maintain their even spacing at that part of the traverse.

According to the present invention this undesirable efiect is avoided by giving to the upper roller a slightly greater peripheral speed than that of the lower roller. By this arrangement there is imposed upon the thread during its upward passage a small additional tension which is subsequently balanced by a corresponding relaxation of tension in the immediately succeeding downward pass of the thread, thus providing a predetermined small stretch on each upward path followed by an exactly equal contraction on the succeeding downward path. This is most conveniently achieved in practice by slightly increasing the diameter of the upper roller at those parts where the thread is wet and under only small tension. In arrangements where the thread is in a wet condition and under small tension for the whole length of the rollers (e. g. where drying is efiected on independent rollers), the rollers may be of equal diameters, the upper roller being driven at a slightly greater angular speed than the lower roller.

In either case the difference in peripheral speed must not be so great as to stretch the thread beyond its true elastic limit at the degree of wetness it possesses at that part of the traverse. We have found that in the case of regenerated viscose artificial thread and, in general, of all commonly produced artificial threads of the modified cellulose (rayon) type, a difierence of 0.16 to (M0 per cent in peripheral speed is sufiicient to correct thread should be under such slight tension during its passage along the pair of rollers as will avoid the imposition of any permanent stretch upon the thread. It is usual in practice to have one roller of the pair approximately vertically above the other, and to have each roller positively driven at the same angular speed. The distance between successive loops is a function of the angle of inclination of the rollers to each other and the tension applied to the thread.

In operating such a continuous process we have observed that at those parts of the traverse where the thread is wet and under only slight tension (e. g. as the thread leaves the spinning bath, and during any succeeding liquid treatment of the thread on the rollers), there is a tendency for the upward-moving part of the loop between the the wobble and maintain the even spacing of the loops without imposing any permanent stretch on the thread. With other artificial threads, such as polyvinyl chloride thread, for example, the appropriate differences in peripheral speed are of the same order but may be less than 0.16% or greater than 0.40%, according to the nature of the thread. An over-correction is easily detected by the appearance of a wobble in the downward-moving part of the loops.

Where, in a continuous process for the production of artificial threads, the thread is subjected to various treatments during its traverse of a pair of inclined rollers and there is a drying stage or stages, the correction for wobble at such drying stage or stages according to the invention involves an increase in diameter of the upper roller which ,will lessen as the thread dries. At such a stage of the traverse it is of advantage so to shape the periphery of the upper roller that at the commencement of the drying stage the difference in diameter from that of the lower roller corresponds with a tension within the true elastic limit of the wet thread, whilst at the end of the drying stage the difference in diameter corresponds with a tension within the true elastic limit of the dry thread.

I prefer to make the necessary adjustment of the diameter of the upper roller by varying, according to the calculated amount, the thickness of rubber or plastic coatings applied to rollers (e. g. cylindrical rollers) of stainless steel or other suitable roller material.

The invention is applicable to rollers which are cylindrical and also to rollers which are conical or frusto-conical or stepped, or which vary in diameter smoothly or in steps along their length.

In the accompanying drawings, which are to be understood as diagrammatic or schematic only,

Figs. 1 to 3, inclusive, illustrate in side elevation different forms and arrangements of roller pairs suitable to employ in practicing the invention, the direction of roller rotation and thread advance being indicated by appropriate direction arrows; and

Fig. 4 is a longitudinal section through a cylindrical upper roller Whose diameter has been adjusted in the preferred manner hereinabove referred to.

Referring to the drawings, Fig. 1 represents the case where the upper and lower rollers, 5, 6, of the cooperating pair are cylindrical and of the same diameter, the thread traverse being indicated at l. The respective rolls are shown provided with individual driving means indicated generally at 8 for the upper roll and 8a for the lower, means 8 being arranged to drive the upper roller at slightly greater angular speed than the lower. In Fig. 2, the upper roller of Fig. 1 is replaced by smoothly conical roller l0, and driving means I I rotates both rollers at the same angular speed; while the arrangement of Fig. 3 resembles generally that of Fig. 2 except that the upper roller has steps l2, l3, 14, instead of being smoothly coned. In Fig. 4, the cylindrical roller l of stainless steel is shown provided with coatings or sleeve I0 of rubber or the like in order to achieve the desired diameter adjustment which, in this instance, is in steps.

I claim:

1. In apparatus for the manufacture of rayon and. generally similar artificial threads by a continuous process wherein the thread issuing from the spinning bath passes around guide rollers on which it is treated with liquid, a pair of mutually inclined guide rollers disposed substantially vertically one above the other, adapted and arranged to be traversed by the thread in a series of spaced helical loops, and means for positively driving both rollers; the peripheries of the rollers being so contoured relative to one another at corresponding parts and the arrangement of the driving means being such that, with said driving means in operation, the peripheral speed of the upper roller, at those parts of the traverse where the thread is wet and under only light tension, is slightly greater than that of the lower roller, whereby'the tension of the thread in its upward path is increased suffioiently to prevent the thread from wobbling but without stretching it beyond its true elastic limit at the degree of wetness it possesses at said parts of the traverse, and the increase in tension thus imposed is balanced by a corresponding relaxation in the immediately succeeding downward pass of the thread.

2. Apparatus as claimed in claim 1, in which the amount by which, at corresponding parts, the peripheral speed of the upper roller exceeds that of the lower roller is, as a maximum, of the order of about 0.40 per cent of the peripheral speed of the lower roller.

3. Apparatus as claimed in claim 2, in which said amount is between about 0.16 per cent and about 0.40 per cent.

4. Apparatus as claimed in claim 1, in which the diameter of the upper roller does not exceed that of the lower roller at the corresponding parts, and the upper roller is rotated by said driving means at a sufiiciently greater angular speed than the lower to impart the necessary greater peripheral speed of the upper roll.

5. Apparatus as claimed in claim 1, in which the diameter of the upper roller exceeds that of the lower roller at the corresponding parts, and the upper roller is rotated at an angular speed not exceeding that at which the lower roller is driven. Y

6. Apparatus as claimed in claim 5, in which the angular speed of both rollers is the same.

7. Apparatus as claimed in claim 1, in Which said driving means rotates the rollers at the same angular speed, the lower roller is substantially cylindrical for at least the greater part of its length, and the upper roller is primarily a cylinder of the same diameter but is provided with a sleeve of suitable plastic material at those parts where the threadis advanced in wet condition, the increase in overall diameterthus effected at each suchpartbeing such as to increase its peripheral speed over that of the corresponding part of the lower roller to the stated extent.

SYDNEY WARREN BARKER.

REFERENCES CITED The following references are of record in the Number Name Date 42,153 Atwood et a1. Apr. 5, 1864 1,977,611 Banigan Oct. 23, 1934 2,002,995 Hartmann et al. May 28, 1935 2,020,057 Hartmann et a1. Nov. .5, 1 .3 2,074,022 Oppenlaender Mar. 16, 1937 2,090,064 Oppenlaender Aug. 17, 1937 2,182,762 Mengeringhausen et al. Dec. ,5, 1939 2,293,995 7 Muller Aug. 25, 1942 2,316,727 Thompson Apr. 13, 1943 2,372,627 Goggin et a1 Mar. 27, 1945 2,410,419 Bellezza, Jr. Nov. 5, 1946 FOREIGN PATENTS Number Country Date 533,837 Germany Sept. 13, 1931 371,910 Great Britain May 2, .1932 509,854 Great Britain July 24, 1939 

